1. Field of the Invention
The present invention relates to a digital data record/play-back system for recording/playing back character data together with digital data.
2. Description of the Related Art
The recent developments of audio equipment are remarkable. A typical example is a compact disk player for playing back data on a disk on which an audio signal is digitized and recorded.
In the field of tape recorders, studies on a digital tape recorder (DAT) system (disclosed in, e.g., U.S. Pat. No. 4,523,237 to S. FUKUDA et al.) for recording/playing data on/from a magnetic tape have been made.
According to the DAT system, an analog audio signal is recorded in the form of a PCM signal on a DAT tape. The PCM signal is played back in the form of an analog audio signal. The DAT system can record and play back PCM signals with higher fidelity than a conventional analog recording system.
In order to best understand the present invention, general DAT standards will be described below.
A DAT (digital audio tape recorder) conference was established in 1981 to achieve DAT design standardization. DATs are classified into a stationary head type DAT (S-DAT) and rotary head type DAT (R-DAT). The R-DAT is considerately used as commercial equipment since it can employ known 1/2-inch VTR techniques. Both the S- and R-DATs have a 48-kH sampling frequency and 16-bit quantitization. A DAT tape has a width of 3.81 mm, and a tape cassette for R-DAT is 73.times.54.times.10.5 mm.sup.3. An R-DAT head drum has a diameter of 30 mm, a speed of 2,000 rpm, and a tape winding angle of 90 degrees. One track (one record of one head, a 23, 501-mm tape portion of 7.5-ms period) is divided into 196 blocks. PCM data including parity data constitutes 128 blocks. One block consists of 288 bits.
When a standard tape cassette is used, the R-DAT can perform 2-hour continuous record/playback operation. Therefore, when a plurality of musical pieces (one musical piece has a length of about 3 minutes) are recorded using this R-DAT, a very large number of musical pieces (i.e., 40) can be recorded. It is very difficult to search a musical piece to be played back from the tape recording such a large number of musical pieces. For this reason, in the DAT standards, a program number can be recorded for each musical piece (program), and a desired program number can be input to easily search the corresponding musical piece. However, in the method using the program number, a user must know a correspondence between musical pieces recorded on the tape and program numbers. For this purpose, program numbers and titles of musical pieces are written on a label of a tape cassette. Thus, a user finds a program number corresponding to a desired musical piece in accordance with the content of this label and can input the program number. However, if a user loses this label, he can hardly know a correspondence between program numbers and titles.
A technique to solve the above problem is disclosed in U.S. Pat No. 4,833,549 invented by I. Yoshimoto et al. In this technique, character code data is recorded into a sub-code recording area of each program, and in a playback mode, this character code data is played back and the character data corresponding to it is displayed.
To know the character data of all of the programs by the technique, considerably much time must be taken. The reason for this is that since the character code data is stored in the sub-code recording area of each program, the character code data is not played back and the character data is not displayed until the area of the DAT tape, in which the program is recorded, reaches the rotary heads.
For this reason, there is the need for the development of a new technique capable of quickly knowing the character data of all of the programs that are recorded on the DAT tape in the format in compliance with the R-DAT standards.